The present invention is directed to carburetors for internal combustion engines and more particularly to carburetors for controlling the air-fuel mixture in response to a signal based on several different parameters related to the operation of the internal combustion engine.
Most carburetors for internal combustion engines are provided with an air cleaner at the air intake side thereof, and are connected at the discharge side to an intake manifold of an internal combustion engine. Such a carburetor is provided with a main fluid passage having a venturi portion therein. A fuel passage is arranged between the venturi and a fuel float chamber so that the fuel is drawn into the venturi portion to be mixed with the air passing therethrough. In order to improve the evaporation of the fuel an air bleed passage is usually arranged between the main air passage upstream of the venturi portion and the fuel passage. Additionally, an actuator of the accelerator pump type is arranged to positively prevent temporary leanness of the air-fuel mixture upon suddenly increasing the degree of throttle opening during acceleration from an engine idling or low speed condition. An actuator having a diaphragm and piston is also arranged to provide fuel to the main fuel system when the intake manifold vacuum pressure becomes lower than a predetermined value to adjust the air-fuel mixture ratio upon full load conditions of engine operation in those situations where the air-fuel ratio is set at an economical level. A choke valve and associated actuator are also arranged to control the quantity of air supplied to thereby obtain a suitable air-fuel mixture in response to engine operating conditions, as for example, when the engine is started in cold conditions.
In view of the foregoing description of a conventional carburetor it is apparent that conventional carburetors are extremely complex in construction and each actuator described above is operated independently. Therefore, the ratio of the air-fuel mixture varies greatly and is not controlled smoothly.